KILLEEN, Texas — The church program pictured an empty road being enveloped by the dark clouds of a sweeping thunderstorm, and the service’s lesson was from Isaiah 35:4, “Be strong, fear not.” The preacher implored those gathered Sunday that they would find hope in God, but also acknowledged the question on everyone’s mind: Why Fort Hood — again?

What would have been a routine Sunday service at Tabernacle Baptist Church just outside the sprawling Texas military base became a tribute to the soldiers killed four days earlier when a fellow service member opened fire. It also offered some catharsis for the community struggling to comprehend Fort Hood’s second fatal shooting rampage in less than five years.

Similar somber religious gatherings were held throughout the military town of Killeen, but there were more questions than answers.

Investigators say Spc. Ivan Lopez, an Army truck driver from Puerto Rico, had argued with soldiers in his unit moments before killing three people and wounding 16 others and then fatally shooting himself. Base officials have said Lopez, who saw no combat during a deployment to Iraq, was being treated for depression and anxiety while being assessed for post-traumatic stress disorder.

The shooting immediately revived memories of the November 2009 attack by Nidal Hassan, an Army psychiatrist who killed 13 and wounded more than 30 people at the base.

The White House said Sunday that President Barack Obama planned to attend an official memorial service Wednesday at Fort Hood.